Manufacture of loaded electric signaling conductors



March 14, 1933. w. 5. SMITH ET AL MANUFACTURE OF LOADED ELECTRICSIGNALING CONDUCTORS Filed May 25, 1931 Patented Mar. 14, 1933WILLOUGHBY STATHAM r orries. 7 1

SMITH, or BENGHAMS,, NEWTO1\T rorrrnronn, HENRY JOSEPH GARNETT, 0FLYMNE, SOLEFIELDS, SEVENO'AKS, AND JOHN NORMAN DEAN, OF ORPINGTON,ENGLAND MANUFACTURE OF LOADED ELECTRIC SIGNALING GONDUGTQBS Applicationfiled May 25, 1981, Serial 110.539,!)64, and. in Great Britain February14, 1931.

This invention relates to improvements in the manufacture of loadedelectric signaling conductors, and more particularly to conductorsloaded with a wire or tape of magnetic material wound upon theconductor.

Such conductors are usually subjected to an annealing treatment in orderto develop magnetic permeability in the loading. After winding on to theconductor the loading tape or wire, the latter, even after annealing,

tends to grip very tightly the conductor with the result thatthemagnetic properties are apt not to be fully developed.

To overcome this strained condition of the loading tape it is thepractice to employ what is known as a spacer between the loading tape orwire and the conductor, which spacer is removed during the subsequentannealing operation.

Various forms of spacer have been proposed, but up to the present allthose which are of a carbonaceous nature, such for example as a papertape or a combustible thread, have not proved satisfactory owing to thedeposits of carbon which are formed in the annealing furnace.

The object of the present invention is to overcome these objections tothe use of acarbonaceous spacer by removing the carbon deposit. I

Experiments have been made with oxygen, which has been introduced incontrolled proportions with the inert gas into the annealing furnacewith the object of reacting with the carbon and other reducing bodiesthat may be present. It has however proved practically impossible tocontrol the inlet of oxygen so that the reducing bodies are fullyoxidized while at the same time the conductor is unattacked by theoxygen.

According to the present invention con ductors having a spacer of acarbonaceous nature, are treated in an atmosphere containing a gas, suchas water vapor containing combined oxygen, which oxygen is capable ofreacting at the temperature of the annealing operation with the carbonor other reducing bodies formed.

An atmosphere consisting of an inert gas e. g. nitrogen admixed withwater vapor the carbon in accordance with the equation C+H O=CO+H p andindeed carbon monoxide has been detected in the gases issuing from thetube at the end where the conductor leaves the furnace. I

The proportion of water'vapor admixed 1 With e. g. the nitrogen does notseem to be at alleritical provided sufficient wateris present to oxidizethe carbonto carbon monoxide. Loaded conductors have been successfullyheat-treated in an, atmosphere consisting almost'entirely ofwater-vapor. The nickel alloy loadingmaterial of the conductorissubstantially unaffected when it has been heat-treated in an atmospherecontaining only a relatively small or moderate proportion ofwater-vapor, but is covered with a very thin film, probably of oxide,when tively thick tape, e.g. .006 inch thick, it is preferable when verythin tape e. ,g. only .001 inch thick is used, to employ such aproportion of water vapor that no oxidation of the metal surface occurs.

The water may be introduced either in the form of steam or as drops ofliquid water through a special entrance tube into the furnace or it maybe sprayed in with the nitrogen.

As has been stated above, the gases issuing from the end of the furnacetube contain carbon monoxide, the highly poisonous nature of which iswell known. In order to prevent this gas escaping into the air of theroom,-an adapter is attached to the exit end of the furnace tube, whichadapter maybe made of copper, brass, gun-metalor anysuitable material.-Two forms of adapters are illustrated in Figures 1 and '2 of theaccompanying drawing which are sectional views. i The adapter mayconsist ofa length of attached to the heating tube indicated at 3 soas'to restrict for a considerable distance that mouth of the heatingtube through which the conductor leaves the furnace, this taperedportion of the tube fitting the conductor fairly closely.

A branch pipe 4 to which a suction pump (not shown) is attached, isfitted to the heating tube at or adjacent the beginning of therestricted portion.

The carbon monoxide and other gases from the furnace are urawn off bythe suction pump through the branch pipe 4 and are prevented fromescaping into the air of the room by the steady intake of air (indicatedby the arrows a) drawn in by the action of the pump through the narrowopening round the emerging conductor. As this causes a vacuum in thetube with con sequent intake of air at the lead in end together 'withthe nitrogen and steam, it is better to provide a partition in theheating tube so as-to form a separate chamber at the exit end and tocontrol the pressure in this chamber so that it is only just below thato1 the atmosphere. Such an arrangement is i shown in Figure 2 in whichthe adapter consists of acylindrical container 5 having axial holes 6for the passage of the conductor. 7 and 8 are inlet and. outlet pipesconnected to the chamber 9 of container 5. Alternatively a controlledamount of air or oxygen may be admitted into the furnace tube at the endof the hot zone, suiticient to oxidize the reducing gases such as carbonmonoxide, hydrocarbons (if present) and hydrogen, to carbon dioxide andwater. The disadvantage of this method is that it is difficult so: toadjust the amountof air or oxygen admitted that the reducing gases arecompletely oxidized while the heated conductor is unattached by theoxygen.

What we claim is I. In the manufacture of aloaded sig naling conductorhaving a spacing materlal applied between the central conductor and theloading material, wherein said spacing material is removed during theprocess of heat treating the conductor in order to provide a spacebetweenthe conductor and the loading material retaining a carbonaceousmaterial, the method of subjecting said car-' bonaceous material to aninert atmosphere containing water vapour, which water vapour reacts atthe temperature of the heat treatment with the retained carbonaceousmaterial for preventing attack of said carbonaceous material upon saidconductor.

2. In the manufacture of a loaded signaling conductor having acarbonaceous material applied between the central conductor and theloading material, wherein said carbonaceous material is removed duringthe process of heat treating the conductor in order to provide a spacebetween the conductor and the loading material while leaving a carbonresidue, the method of subj ecting said carbon residue to an atmosphereconsisting of a mixture of nitrogen and water vapour for the purpose ofdissipating said carbon residue and preventing the at-

